The Republican-led Congress began its first session of the Donald Trump era in turmoil on Tuesday as the House of Representatives backed away from a decision to defang an ethics watchdog after a public outcry, including a dressing-down from the president-elect.

With Trump set to be sworn in as president on Jan. 20, Republicans will control both the White House and Congress for the first time since 2007, and they were set to begin laying plans for enacting his agenda of cutting taxes, repealing Obamacare and rolling back financial and environmental regulations.

But the moment was overshadowed by a surprise move by Republicans in the House of Representatives in a closed-door meeting late on Monday to weaken the independent Office of Congressional Ethics, which is in charge of investigating ethics accusations against lawmakers.

Trump, who campaigned on a pledge to "drain the swamp" and bring ethics reforms to Washington, was not pleased.

"With all that Congress has to work on, do they really have to make the weakening of the Independent Ethics Watchdog, as unfair as it may be, their number one act and priority," he said on Twitter on Tuesday.

"Focus on tax reform, healthcare and so many other things of far greater importance!"

The ethics office was created in 2008 following several corruption scandals but some lawmakers have charged in recent years that it has been too quick to investigate complaints from outside partisan groups.

Lawmakers wanted to have greater control of the watchdog, and inserted changes into a broader rules package, set to pass when the House convenes on Tuesday.

Even before Trump's tweet, many House Republicans, including top leaders, opposed the measure and worried about its ramifications. Trump's tweet prompted an emergency meeting and a quick change of course by Republicans.

"It was taken out by unanimous consent ... and the House Ethics Committee will now examine those issues," said AshLee Strong, a spokeswoman for House Speaker Paul Ryan.